Get some element in an array with a specific condition

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hello i have a question:
if i have this array : dd=[(1,'a',2),(2,'b',4),(5,'a',4)]
i want to get only d1 from dd / d1=[(1,'a',2),(5,'a',4)] for dd[i][1]='a'
how i can?

What I have tried:

>>> d1=[dd for dd[i][1]='a' for i in range(0,3)]
File "<stdin>", line 1
d1=[dd for dd[i][1]='a' for i in range(0,3)]
^
SyntaxError: invalid syntax

Posted 16-Mar-17 3:41am

Member 11436383

Updated 16-Mar-17 4:33am

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2 solutions

Solution 1

See The Python Tutorial — Python 3.4.5 documentation[^].

Use a list comprehension such as:

Python

[x for x in dd if x[1]=='a']

which gives: [(1, 'a', 2), (5, 'a', 4)]

Posted 16-Mar-17 4:25am

Richard MacCutchan

Updated 16-Mar-17 4:34am

v2

Comments

Member 11436383 16-Mar-17 11:10am

Thank You

Richard MacCutchan 16-Mar-17 11:20am

I strongly recommend you go and work through the tutorial. You will learn far more than you will by posting questions here.

Member 11436383 16-Mar-17 11:26am

So this website is for: ?

Richard MacCutchan 16-Mar-17 12:29pm

It is for serious technical questions, where the questioner has done most of the work. Not really for ones like the above that can easily be solved by looking at the documentation or tutorials.

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Peter Leow · Accepted Answer · 2017-03-16T04:33:00

Solution 2

You have a list of tuples, to get those tuples whose second element is 'a', make use of list comprehension like this:

dd=[(1,'a',2),(2,'b',4),(5,'a',4)]

d1=[x for x in dd if x[1] == 'a']

print (d1)

You should get

[(1, 'a', 2), (5, 'a', 4)]

Posted 16-Mar-17 4:33am

Peter Leow

Updated 16-Mar-17 4:34am

v2